The induction of crown gall tumors by bacteria in the genus Agrobacterium will be utilized as a model system for studying the genetics and biochemistry of tumor induction. Genetic transformation and transduction will be used to analyze the cistrons responsible for the oncogenic properties of A. tumefaciens. The precise steps in the sequential conversion of normal cells to tumor cells will also be explored by use of procaryotic-specific antibiotics, temperature sensitive mutants, and mixed-inoculation techniques.